1. Field
One or more aspects of embodiments of the present disclosure relate to a material for an organic electroluminescent device and an organic electroluminescent device including the material. The organic electroluminescent device including the material of embodiments of the present disclosure can be driven at a low voltage in a blue emission region and can exhibit high emission efficiency.
2. Description of the Related Art
Recently, an organic electroluminescent display (hereinafter, “organic EL display”) has been actively developed as an image display apparatus. The organic EL display, unlike a liquid crystal display or the like, is a self luminescent type (or kind) of display which is capable of displaying images via light emission of a luminescent material including an organic compound. For example, holes and electrons injected from an anode and a cathode can be recombined in an emission layer including the luminescent material to emit light.
For example, an organic electroluminescent device (organic EL device) may include an anode, a hole transport layer positioned on the anode, an emission layer on the hole transport layer, an electron transport layer on the emission layer, and a cathode on the electron transport layer. Holes are injected from the anode, and are transported via the hole transport layer into the emission layer. Electrons are injected from the cathode, and are transported via the electron transport layer into the emission layer. The holes and the electrons injected into the emission layer are then recombined, and excitons are generated in the emission layer. The organic EL device emits light using light generated by the radiation deactivation of the excitons. The organic EL device is not limited to the aforementioned configuration, and may include modifications thereof.
The organic EL device included in a display device is required to be driven at a low voltage and have high efficiency and long life. For example, in a blue emission region, the driving voltage of an organic EL device may be too high and the emission efficiency thereof may be insufficient when compared to those in a green emission region and/or a red emission region. To realize a low driving voltage, high efficiency, and long life of the organic EL device, the normalization, the stabilization, and/or the like of the hole transport layer may be examined. For example, an aromatic amine compound can be utilized as a material for the organic EL device, however the carrier tolerance of such material is relatively low, and thus the life of the organic EL device may remain low.
To increase the life of the organic EL device, an amine derivative substituted with, for example, a heteroaryl ring has been proposed. However, the organic EL device using the above-described material has not been shown to sufficiently realize low driving voltage, high emission efficiency, and long life, and thus there is still a need for an organic EL device having low driving voltage, high emission efficiency, and long life. Particularly, since the emission efficiency of the organic EL device in a blue emission region is relatively low when compared to that in a red emission region and/or a green emission region, increased emission efficiency in the blue emission region is required. Accordingly, there is a need for the development of a novel material capable of realizing an organic EL device having low driving voltage, high emission efficiency, and long life.